RubyGems version 2.6.12 and earlier is vulnerable to maliciously crafted gem specifications to cause a denial of service attack against RubyGems clients who have issued a query
command.
blog.rubygems.org/2017/08/27/2.6.13-released.html
www.securityfocus.com/bid/100579
www.securitytracker.com/id/1039249
access.redhat.com/errata/RHSA-2017:3485
access.redhat.com/errata/RHSA-2018:0378
access.redhat.com/errata/RHSA-2018:0583
access.redhat.com/errata/RHSA-2018:0585
github.com/rubygems/rubygems/commit/8a38a4fc24c6591e6c8f43d1fadab6efeb4d6251
hackerone.com/reports/243003
lists.debian.org/debian-lts-announce/2018/07/msg00012.html
security.gentoo.org/glsa/201710-01
www.debian.org/security/2017/dsa-3966